Telescoping vacuum tube shield



April 1952 E. F. STAVER TELESCOPING VACUUM TUBE SHIELD 3 Sheets-Sheet 1 Filed July 10, 1956 INVENTOR. EDWARD F 57/4V5/Q ATZOZ/VEXS M M BY 1:21.15.

7 M O O icqlz.

April 3, 1962 Filed July 10, 1956 E. F. STAVER TELESCOPING VACUUM TUBE SHIELD 3 Sheets-Sheet 2 INVENTOR. EDWARD F. STA VER B%MMM ATTORNEYS April 3, 1962 E F. STAVER 3,023,444

TELESCOPING VACUUM TUBE SHIELD Filed July 10, 1956 3 Sheets-Sheet 3 IN VEN TOR. EDWARD F. S TAVER ATTORNEYS United States Patent O This invention relates to vacuum tube shields, and more particularly to a telescopic and preferably non-removable shield.

Difiiculty has sometimes arisen following the servicing of radio and television receivers, because of failure to replace'the vacuum tube shields. In other cases they have been left loose in the set and may cause difiiculty such as short circuit. The problem has become more serious now with the trend toward printed circuits, which often are printed on the top as well as the bottom side of an insulation chassis plate, thus exposing hot wiring to a loose or mislaid tube shield. The problem is particularly acute with receivers using metal cabinets, for in such case a loose tube shield may form a short circuit from a hot printed chassis conductor to the metal cabinet itself, with consequent danger to anyone touching the cabinet.

The primary object of the present invention is to generally improve tube shields. A more particular object is to overcome the foregoing ditl'iculties, which I do by means of a novel telescopic tube shield the lower end of which maybe permanently'secured to the tube socket or/ and the chassis carrying the same. The shield is telescoped to expose the upper portion of the tube for removal or replacement, and later is extended to shield the tube.

A further object of the invention is to keep the telescopic shield in extended relation, for which purpose'detent means may be provided. Another object is to prevent removal or complete separation of the sections, for which purpose they may be provided with positive stops. Still another object is to steady the tube and the shield against relative movement, and with this in view an inner section of the shield is preferably provided with spring fingers which bear flexibly against the glass envelope of the tube. A still further object of the invention is to improve the electrical contact between and the sliding action of the sections of the shield, which I do by the provision of a plurality of longitudinal channels in one section and mating projections or stops in another section, said projections or stops riding in said channels.

Another object of the invention is to provide means to secure the shield to a vacuum tube socket or/and the chassis carrying the socket. This may be done by the provision of outwardly projecting perforated ears at the lower end of the shield, particularly for use with laminated sockets. To lessen tooling expense resulting from considerable variation in the size and location of such ears and the spacing of their mounting holes in tube thereto, and the shield itself being provided with means for mounting the socket on a chassis plate, as by crimping,

or by the use of ears and eyelets.

Still another object of-the invention is to providea telescopic shield which locks in extended position by a slight rotation 01' twist of one partrelative to the other, and still another object is to provide-the twist lock it- 3,028,444 Patented Apr. 3, 1962.

2 self with detent means to inhibit reverse rotation in order to additionally hold the shield in locked condition.

, Afurther object of the invention is to provide a telescopic shield provided with means for mounting the same on a printed circuit board over a socket of the raised type often used on printed circuit boards.

To accomplish the foregoing objects, and other more specific objects which will hereinafter appear, my invention resides in the telescopic shield elements, and their relation one to another'and to the socket and tube with which the shield is used, as are hereinafter more particularly described in the following specification. The specification is accompanied by a drawing, in which:

FIG. 1 is an elevation of a telescopic tube shield embodying features of my invention, with the shield extended; p

FIG. 2 is an elevation looking at .an angle of 45 relative to FIG. 1, with the shield telescoped or shortened;

FIG. 3 is a view looking in the same direction as FIG. 2, but showing the lower. section only of the shield;

FIG. 4 is a horizontal section taken approximately in the plane of the line 44" of FIG. 1, with the socket omitted;

FIG.. 5 is a fragmentary vertical section drawn to en larged scale at the arrows 55 in FIG. 1; I

FIG. 6 is a fragmentary section similar to FIG. 5 but showing a modification;

FIG. 7 is a front elevation of a modified telesocpic shield secured to a different type ofsocket;

FIG. 8 is a horizontal section taken approximately in '1 the planeof theline 8-8 of FIG. 7;

' FIG. is a similar view of a modified ear plate;

FIG. 14 is a vertical section through the lower section of a tube shield having downturned flexible fingers for engaging the glassenvelope of the vacuum tube;

FIG. 15 is a schematic view showing a telescopic-tube shield having three sections;

FIG.- 16 is a partially sectioned front elevation showing a shield which combines the features of FIGS. 1 and 11 of the drawing;

FIG. 17 is asection taken approximately in the plane of the line 17-47 of FIG. 16;

FIG. 18 is a front elevation of a shield having a twist lock and a modified bottom plate; 4

FIG. 19 is a bottom-plan view of the shield shown in FIG. 18; l

FIG. 20 is a section taken approximately in the plane FIG. 21 is a fragmentary'section taken approximately in the plane of the line 21-421 of FIG. 18;

FIG. 22 is a vertical section taken approximately in theplane of the line 2222 of FIG. 20;

FIG. 23 is a partially sectioned elevation of a shield having a modified saddle intended to be combined with a molded socket; 4

FIGJ24 is a fragmentary vertical section showing the shield combined with a molded socket, and is taken approximately in the plane of the line 24-24 of FIG. 25;

FIG. 25 is a bottom plan view of the combined shield and socket shown in FIG. 24;

FIG. 26 is a partially sectioned elevation of a shield having a saddle applied to a printed circuit board using and 27, but modified to avoid printed circuit lines on top 7 of the board;

FIG. 29 is a side elevation of the lower part of the saddle shown in FIG. 28;

FIG. 30 is an elevation of the lower part of a shield having a saddle modified to provide a resilient or snapfit mounting on a printed circuit board;

FIG. 31 is a side elevation of the lower part of the saddle shown in FIG. 30;

FIG. 32 is a front elevation of a shield generally like that shown in FIG. 26, but modified to clear a small resistor orother component located immediately adjacent the socket;

FIG. 33 is an elevation of the lower part of a shield having a modified lower end with integral lugs;

FIG. 34 is a bottom view of'the shield section shown in FIG. 33;

FIG. 35 is a side elevation of the lower end of the shield shown in FIGS. 33 and 34;

1 FIG. 36 is a partially sectioned elevation of the lower part of a shield having still another form of raised saddle which may be stamped instead of being drawn;

FIG. 37 is a bottom view of the same;

FIG. 38 is a side elevation of the lower end of the same; and

FIG. 39 is a partially sectioned elevation of the lower end of a telescopic shield combined with a molded socket.

Referring to the drawing, and more particularly to FIGS. 1 and 2, I there show a vacuum tube 12 of the miniature type, received in a socket 14 carried by a chassis plate 16, and enclosed by a conductive and preferably metallic tube shield. I he tube shield comprises a plurality of generally cylindrical conductive sections 20 and 22 of graduated diametensuch that they may telescope one over the other to a shortened length, as in FIG. 2, which exposes the upper portion of the tube 12 for removal or replacement, and an extended length, as in FIG. 1, which shields the tube.

One end of the shield, specifically the lower end of the lower section 20, is secured to the socket 14 or/and the chassis 16 carrying the same. The tube shield preferably includes means to prevent complete separation of the sections, and referring to FIG. 3 it will be seen that the inner section 20 has outwardly struck stops 24 at its upper end. Referring to FIGS. 1 and 2, the outer section'has outwardly struck longitudinal channels 26 which terminate near the lower end of the section. The stops 24 ride slidably in the channels 26, as shown in FIG. 4, and serve to prevent upward removal of the outer section 22 from the inner section 20. This action will also be clear from inspection of FIG. 5.

The fit between the parts is preferably made frictional in" order to provide good electrical contact therebetween,

,and to make sure that the sections remain in extended relation unless intentionally telescoped.

If desired the parts may be provided with additional detent means to releasably'hold the sections in extended relation, and referring toFIG. 6; it will be seen'that the lower end of channel 26 is not only terminated as shown at 28 in FIGS. and 6, but also is indented a little above the termination 28as shown at 30. The stop projection 24 is matingly recessed as shown at 32, and it will be evident that with this arrangement the detent parts 30 and 32 come together with a snap engagement when the outer section of the shieldis pulled all the way up. This effectively prevents accidental lowering of the shield, but, of course,

anintentional push will override the detent action and shorten the shield.

I't-will be understood that the'detentparts 30 and 32 inay, if desired, be used without the positive stop 28, in which case the detent action will arrest extension of the shield and inhibit removal of the upper part of the shield without, however, positively preventing the removal.

An additional feature of the shield is the provision of yieldable fingers-to engage the glass envelope of the tube.

In the present case there are two such fingers, shown at 34 in FIGS. 2 and 3 of the drawing. They are formed integrally with the inner section 20, and project inwardly somewhat in order to bear yieldably' against the tube envelope. It will be understood that a different number of fingers, for example four such fingers may be employed, instead of two as here shown.

Referring now to FIGS. 7, 8 and 9 of the drawing, 1' there show a modified form of telescopic shield in which the inner section 49 has the longitudinal channels 42, and these are pressed inward instead of outward. The outer section 44 has mating projections or stops 46formed at its lower end. The projections 46 ride frictionally in the channels 42, and by forming the top edge of inner section 40 outward, as shown at 48 in FIG. 9, the projection 46 acts as a stop to prevent removal of the outer section 44 from the inner section 40. I

If an additional detent action is desired to prevent accidental lowering ofthe shield, this may be provided as shown in FIG. 10, in which a part 50 of the inner shield, preferably at the upper end of each channel 42, is struck outward, and a part 52 of the outer shield is matingly struck outward, so that the parts spring into snap engagewill inhibit removal of the upper part of the shield, without positively preventing removal. I

Reverting to FIGS. 1, 2 and 3, the socket 14 there shown is of the molded insulation type. It maybe molded of a suitable one of the known plastics, or a ceramic material. The usual ring of conventional metal contacts is disposed in the insulation body, and the soldering lugs or tails from these contacts project downwardly at the bottom, as shown at 54. A feature of the present invention is that the lower shield section 20 is permanently secured to the insulation body 14, and indeed acts as a means to secure the socket to the chassis plate 16. For this purpose the insulation body is preferably inwardly stepped, as shown at 56 in FIG. 3. It has appropriate recesses, and parts of the shield are indented, as shown at 58, tolock the shield and socket together, the upper part of the socket being received within the lower end of the shield as shown. The shield and socket are relatively immovable both rotationally and axially. v

In the present case the means to secure the assembly to the chassis plate is as follows. The shield is stepped inthrough the hole it is spun or crimped outwardly, as shown at 64 in FIGS. 1 and 2. This permanently secures both" v the shield and the socket to the chassis.

Some tube sockets, particularly those of the laminated or wafer type, are provided with diametrical perforated ears, for attachment to a chassis by means of rivets or eyelets. Such an arrangement is shown in FIG. 7, in

which the laminated insulation body 66of the tubesocket is secured to a chassis plate 68 by means of rivets or eyelets 70. For use with such a socketthe tube shield is preferably provided with ears shown at 72 in FIGS. 7-and- 8. In the present case these have been formed integrally with and bent outwardly from the cylindrical section 40. The ears are preferably perforated at the same spacing as the ears of socket 66, so that the eyelets 70 may be usedto fasten both the shield and the socket to the chassis plate 68. In FIG. 7 the socket is shown underrnounted, that is beneath the chassis plate, which is preferred, but it will be understood that it may also be secured above the chassis plate. a

For miniature tubes the telescopic shield need be made in only two diameters, one for the seven-prong tubes and the other for the nine-prong tubes. It may also be made in several lengths to take care of tubes which difler substantially in length. However, there is less standardization of the ears and holes for the eyelets 70 for mounting the sockets, and to avoid excessive tooling costs, the ears may be made separately instead of integrally with the shield.

Such an arrangement is shown in FIG. 11, in which the ears 74 form a part of a flatstamping 76 of sheet metal. The shape of this stamping is shown in FIG. 12, and it has a large hole 78 somewhat smaller than the shield diameter. The latter is shouldered or stepped inwardly slightly,'and subsequently is spun or crimped' to the plate as shown at 80 in FIG. 11, thus permanently securing the two parts together. FIG. 13 shows a plate '82 having the same size hole 78, :but with cars 83 and holes 84 dimensioned differently from those in FIG. 12. It will be understood that a number of different plates may be assembled with the same dimension of shield, the plates each being permanently crimped to a mating shield, as shown in FIG. 11.

It will also be understood that a shield using the outwardly struck channels of FIG. 1 may be formed with ears, as shown in FIGS. 7 and 11, and similarly that a shield with the inwardly struck channels of FIG. 7 may be permanently secured around a molded insulation or ceramic socket as shown in FIG. 1, these features being interchangeable.

In FIGS. 1 and 7 the flexible fingers for hearing against the tube have been shown projecting upward. However, these fingers may'instead be turned downward, and such a modification of the invent-ion is shown in FIG. 14, in

which the yieldable fingers 86 have been bent downward from the top edge of the lower inner section 88 of the tube shield. This figure also illustrates the use of four instead of two fingers. p

The upper section of the shield has been omitted, but it will be .understood that in the illustrated construction, section 88 has inwardly struck longitudinal channels 90, and that the upper section is provided with inwardly struck stops, as described in connection with FIGS. 7-10. However, the downwardly bent fingers 86 may also be employed when using outwardly struck channels on the upper section cooperating with stops on the lower section, as described in connection with FIGS. l-6 of the drawing. Moreover, section 88 may be secured to a socket and chassis as shown in FIGS. 1 and 3, instead of being provided with ears as shown, and the ears may be non-integral, as shown in FIG. 11, these ideas all being interchangeable.

As so far described the tube shield has only two telescopic sections, but more than two sections maybe used, and in certain cases may be desirable. For example, if a tube is quite short, three sections may be desired in order to expose adequate length of tube for removal and replacement. If a tube is very long, and if the shield sections happen to be made by drawing, three sectionsmay be desired in order to avoid a deep drawing operation. However, it should be understood that it is not essential to make the sections by a drawingoperation, or to provide seamless sections as here shown, for sheet metal may be rolled to cylindrical shape and seamed at the meeting edges; I

A'tube shield using =three'sections is "schematically 6 or/ and detent means to arrest extension of the shield, and to hold the'shield extended.

It will be understood that the lower section 92 may be secured to a socket and chassis as shown in FIGS. 1 and 3, instead of as shown in FIG. 7; that. grooves, when employed, may be outward as shown in FIG. l',or inward as shown in FIG. 7; that separate ears may be added as shown in FIG. 11; and that either stop means or detent means, or both, may be employed as shown in FIGS. 5,

6, 9 and 10.

It will be understood that while I have shown vacuum tube sockets of the type using conventional soldering lugs or tails, the invention is also applicable to sockets in which the tails or soldering lugs have been modified for use with printed circuits or for use with the so-called pot soldering process.

The shield may be made of any suitable conductive material, the more usual materials being tin plated or cadmium plated steel, but for more severe service conditions, as for example in military equipment, the shield may be made of brass or copper. The shield is preferably provided with both detent and stop means, and when the shield has ears, as in FIG. 7, the parts are then preferably assembled after forming the detent means but before forming the positive stop means. The latter are formed by an extra tool operation after the sectionshave been assembled. In the'case of a shield secured to a molded socket without the use of diametrical ears, the detent and stop means may be formed before assembly because the parts may be assembled by sliding the outer section upwardly over the lower end of the inner section.

Referring now to FIGS. 16 and 17, I there show a telescopic shield which combines the structure of FIGS.

1 and 6 witli the assembled bottom plate of FIGS. 11 and 1.2.. The shield comprises an upper section 100 channeled at 102, and a lower section 104 having outwardly struck stops which ride in the channels 102. The apertured ears 106 form part of a stamped plate 108 which is secured'to the lower end of section 104 by shouldering or stepping the shield inward somewhat to receive the plate, and subsequently spinning or crimping the lower edge of the shield outward against the bottom of the plate,, thus permanently securing the parts together, as shown at 1 10. A practical manufacturing advantage is that a variety of sizes and shapes of plate 108 may be assembled to standard shieldsections, which for the socalled miniature tube need be made in only two diameters.

' FIGS. 18 through 22 illustrate a different and preferred locking means to hold the shield sections in extended relation. Referring thereto, the upper section 112 has channels 114 and cooperates with a lower section 116 differs in having short horizontal channels 118 extending in otfset relation from the lower ends of the longitudinal channels 114, whereby the upper section 112 may be turned somewhat after being pulled. upward,. and the resulting entry into channels 118 of the stops 120 (FIGS. 21 and 22) at the upper" endot the lower section 116 serves to lock the sections in extended relation.

In addition, the horizontal channelsy118 may, if desired, be necked very slightly at a point between the vertical channels 114 and the horizontal channels 118, as shown at- 122, thereby providing an auxiliary detent means'which holds the outer section in turned or twisted relation to the inner section. The lock or detent provided at 118 has the advantage of being positive, in contrast with the detent lock shown inFIGS. 6 and 10, and the auxiliary detent-action at 122' (FIGS. 18 and 21) may be'kept rather .light, yet is adequate because it is appliedonly to the twisting of the upper section, rather than tothe'telescoping of the sections. The ofiset position of the stop 120 is shown in FIG. 22.

FIGS. 18-22 also show a slightly modified bottom plate 124. In this case the bottom plate is dished'upward somewhat, as shownat 126 (FIG. 18), instead of being flat as shownin FIGS. 11 and 16. One advantage is that the plate 124 is stiffened, and if desired a lighter gauge metal may be used. Another advantage is that the outwardly spun edge 128 of the lower shield section 116 is raised above the bottom of the plate, thereby provid ing a flush or truly flat bottom.

In this shield the diametrically opposite sides of the lower section 116 are indented or flattened somewhat near the lower end, as shown at 130. This is of advantage when working with certain sockets having corresponding indentations, and establishes a desired orientation between the socket and the ears. It may incidentally provide greater clearance around the eyelets passing through the ears.

FIGS. 23, 24 and 25 show a telescopic shield with a twist lock'sirnilar to that shown in FIGS. 18*22 but with a saddle modified for use with a molded socket. In

7 FIG. 23 the socket has not yet been added. Referring to that figure, the telescopic sections 132 and 134 may be like those already described, and the saddle similarly has ears 136, and is secured by a crimped connection shown at 13-8, but the saddle in this case is drawn more deeply, as shown at 140. The depth at 140 corresponds to the height of the part 142 (FIG. 24) of a molded socket 144. The socket may be inserted upwardly from beneath into the saddle, following which the edges of the saddle between the ears 136 may be turned inward, as shown at 146 in FIGS. 24 and 25. The resulting structure has'ears 136 which may be eyeletted directly to a metal chassis, and the shield itself then holds the socket in position.

FIGS. 26 and 27show still another form of the invention which is adapted for mounting on printed circuit boards using raised sockets. In FIG. 26 the socket 150 is a laminated socket of a type currently in use. The pin grip portions are not shown in FIG. 26, but the older flat soldering lugs are replaced by tubular support posts 152 which are shown. The lower ends of the posts are split and resilient and shaped for a snap fit insertion into a ring of mating holes in a printed circuit board, suggested in broken lines 154. The printed circuitry on .thebottom of the board leads to these holes, and is ready for soldering to the downwardly projecting tips of the posts 152. This soldering may be performed by the dipping or so-called"pot soldering method. The socket shown is made by Industrial Hardware Mfg. Co.,' Inc. of NYC. The insulation of such a socket is raised substantially higher than the. printed circuit board, and the telescopic shield sections 156, 158'are provided with a saddle 160 whichis drawn deeply, as shown by the high annular cylindrical. wall 162, thereby accommodating the raised socket 150. The wall 162 is-provided with a plurality, in this case two diametrically opposed lugs 164, best shown in FIG. 27. These lugs are'desi gned to pass through mating holes in the printed circuit board, following which they may be bent outward, as shown in broken lines at 164', thus anchoring the shield in position. a

Ordinarily there willi be printed circuit lines leading to at least one and more often bothof the lugs 164. This is done in order'to effectively ground the shield. In such case the lugs become soldered to the ground lines during the pot soldering operation, thus additionally securing the shield to the printed circuit board. 7

In some cases the printed circuit board is printed on the top surface as well as the bottom surface, and. in such case the bottom edgeof the peripheral wall 162 of the saddleisnaised in order not to short circuit theprinted conductors: Suchan arrangement isshownin FIGS. 28 and 29, referring to which the-shieldsection 170 is the lower of telescopically related tube sections exactly like those shown in FIGS. 18, 23 and 26, the said secvided with lugs 174, but in the present case the bottom edge 176 of the saddle is raised, or viewedditferently,

the lugs 174 are stepped or shouldered at 178, as is best shown in FIG. 29. Thus the insertion is limited by the shoulders 173 to a desired amount much as in 27, i and the lugs similarly may be bent beneath the printed circuit board to lock the shield in position.

If desired the initial attachment of the shield to the printed circuit board may use a snap fit connection, thereby dispensing with the need to bend lugs beneath the board. Such an arrangement is shown in FIGS. and 31 in which the shield section 13% is the lower of a pair of telescopic sections provided with a twist locking action, as previously described. The saddle 182 is assembled tothe lower section by means of a crimped connection similar to that shown in FIGS. 18, 23 and 26. The lugs 184 are so shaped as to enter mating holes with a resilient or snap action. The lower edge 186 of the saddle may be raised above the chassis board by stepping or shouldering the lugs, as shown at 188. When this is not necessary the saddle wall may be of full depth as in FIG. 26, the snap lugs 184 replacing the lugs 164.

It will be understood that the snap action is adequate to hold the shield in position on the chassis until and.

during the pot soldering operation, which then additionally secures the shield in position.

FIG. 32 shows a shield similar to that shown in FIGS.

26 and 27,. but modified to permit the mounting of a smallresistor or other component at a point immediately adjacent the socket. The shield comprises telescopic sections 190 and 192 provided with a twist lock at 194.

A deeply drawn saddle 196 is secured to lower section 192 by a crimped connection at 198. .The saddle is 200, and if desired spring lugs may be provided instead of the straight lugs shown. The side wall of the saddle 196 is cut away, as shown at 202, to make an opening which is suitably located to come over a small resistor mounted on top of the printed circuit board. Thus the saddle is modified to meet a particular chassis layout problem, and this again illustrates the advantage of ver-- satility when adding a separate saddle by a connection as shown in FIGS. 18, 23, 26, etc.

Nevertheless, if desired, the mounting lugs may be" formed integrally with the lower shield section. Such an arrangement is illustrated in FIGS. 33, 34 and 35 0f the drawing, referring to which the lower end of the lower section is shown at 204. It will be understood that the parts of the shield not illustrated conform to those previously described, preferably using the twist lock shown in FIGS. 18, 23 and 26. jShield section 204 has support legs 206formed integrally therewith, and these are preferably stepped or shouldered, as shown at 208. The narrowed lower ends 210 are dimensioned to pass through holcs'in a printed circuit board 212. They may be bent after insertion, or they may be preliminarily bent'as shown, to provide a resilient snap action. If desired the lower end of shield section 204 may beprovided with .at the ends of a diameter which is not perpendicular to the diameter connecting the mounting lugs 210. This dif'. ference is intended to accommodate a printed circuit board which is printed on top as well as on bottom,

and the lugs 214 are positioned as shown in order to avoid'contact with printed circuit lines.

The lug and tab arrangementshown in FIGS. 33-35 may be used on a saddle which is made separately from and subsequently secured to a lower shield section, as previously described.

A somewhat modified saddle which is thus secured to the telescopic sections is illustrated in FIGS. 36-38 of the drawing. One main difference between this saddle and those described in connection with FIGS. 26-32 'is that the present saddle may be made by a simplerstamping operation, without necessitating a drawing operation. Referring to FIG. 36, the telescopic sections 220 and 222 maybe like those previously described, and may be provided with a twist lock 224, as previously described. The saddle 226 is similarly secured to lower section 222 by a crimped connection shown at 228. In a sense it may be said that this saddle is like the saddles shown in FIGS. 11 and 16, except that the ears are greatly prolonged and are bent downward to provide support legs 230, terminating at their lower ends in mounting lugs 232. In FIG. 38 it will be seen how leg 230 is stepped or shouldered at 234 at the upper end of lug 232, thus limiting the insertion of the saddle into the mounting holes provided in a printed circuit board. The lugs 232,

may be bent after insertion or, as here illustrated, may be bent initially to provide a resilient snap engagement in the printed board. The legs 230 serve to raise the lower end of the shield sections an amount suflicient to accommodate a raised socket such as that shown in FIG. 26. Because there is no'drawn side wall around the saddle there is no problem of avoiding printed circuit lines on top of the board. To help stilfen the desired right angle relation between the top plate 226 of the saddle, and the upright legs 230, the corners may be indented, as shown at 236. In the present case there are two such indentations for each leg, and they may be made of sufficient depth to rigidity the structure, without actually cutting through the metal.

FIG. 39 illustrates an assembly of telescopic shield with a molded socket, but shows a different method of assembly from that described in connection with FIG. 24. In the present case the molded socket 240 has a peripheral ledge of increased diameter at 242. This raised portion is located intermediate the'ends of the socket, thus providing a portion of reduced diameter 244 at the top of the socket. The shield section 246 is the lower of a pair of telescopic sections, preferably provided with a twist look, all as previously described, and the lower section is secured to a mounting plate 248 by means of an inwardly stepped and crimped connection shown at 250 and similar to those previously described.

With such a construction the socket 240 may be pushed through the lower end of the shield from above until the ledge 242 comes to rest on top of the crimped connection 250. The side wall of'shield section 246 is then indented at a plurality of points, say four points, as shown at 252, the indentations coming immediately above the ledge 242 of the socket, in order to lock the socket against upward movement.

Here again, as .in previous illustrations, the lower shield section 246 may be flattened slightly at diametricalorientation between the socket and the shield, or morespecifically, between the socket and the ears of the plate 248. Such flats for purpose of orientation are also shown at 139 in FIG. 18; at 260 in FIG. 23; at 262 in FIG. 26; at 264 in FIG. 28; at 266 in FIG. 30; at 268 in FIG. 32; and at 270 in FIG. 36.

It is believed that the construction and method of use of my improved telescopic tube shield, as well as the advantages thereof, will be apparent from the foregoing detailed description. In its preferred form the shield cannot be lost or mislaid, nor can it shake loose from the tube accidentally, with possibility of short circuit. There is no forgetting to return the shields after a servicing operation, nor returning'of shields to a wrong or previously unshielded tube. The flexible fingers of the shield, when used, act as a shock mounting for the tube, and help to steady it and to prevent unintended release of the same from the socket. The shield may be combined with a tube socket, and may even act as a mounting means for the same.

The shield may be provided with a twist lock which is smooth .and easy in action. The lower end of the shield may be provided with any of a large number of mounting plates or saddles adapted for use with printed circuit boards as well as metal chassis plates.

The present application is a continuation-in-part of my earlier application Serial No. 497,091, filed March 28, 1955, now abandoned. 7

It will be understood that while I have shown and described my invention in a number of preferred forms, changes may be made in the structures shown without departing from the'scope of the invention, as sought to be defined in the following claims. In the claims the terms vertical and horizontal are used in a relative .sense, for in practice the tube may be used in a horizontal or angular position, instead of the upright position shown in the drawings.

I claim:

1. Avacuum tube shield for a tube used in an electronic device, said shield comprising two generally cylindrical conductive sections, one section having a diameter slightly greater than the other so that one section is telescopically slidable over the other to a shortened length which exposes the upper portion of the tube for seizure for removal or replacement, and an extended length which shields the tube, and means to secure one section of said shield to said electronic device, one section having a plurality of vertical channels terminating at the adjoining ends, the other section having mating stops at the adjoining ends, said stops riding in said channels and serving to arrest upward removal of one section from the other section, horizontal channels extending in ofiset relation from the ends of the vertical channels, whereby said outer section may be turned somewhat after being pulled upward, the resulting entry of the stops into the horizontal channels serving to hold the sections in extended relation.

, 2. A vacuum tube shield for a tube used in an electronic device, said shield comprising two generally cylindrical conductive sections, one section having a diameter slightly greater than the other so that one section is telescopically slidable over the other to a shortened length which exposes the upper portion of the tube for seizure for removal or replacement, and an extended length which shields the tube, and means to secure one section of said shield to said electronic device, one section having a plurality of vertical channels terminating at the adjoining ends, the other section having mating stops at the adjoining ends, said stops riding in said channels and serving to arrest upward removal of one section from the other section, horizontal channels extending in ofiset relation from the ends of the vertical channels, whereby said outer section may be turned somewhat after being pulled upward, the resulting entry of the stops into the horizontal channels serving to hold the sections in extended relation, said horizontal channels heingneckecl slightly at a point between the vertical channels and the ends of the horizontal channels, thereby providing auxiliary detent means to hold the outer section inlocked relation to the'inner section.

3. A vacuum tube shield for a tube used in an electronic device, said shield comprising two generally cylindrical conductive sections, one section having a diameter slightly greater than the other so that one section is telescopically slidable over the other to a shortened length which exposes the upper portion of the tube for seizure for removal or replacement, and an extended length which shields the tube, and means to secure one section of said shield to said electronic device, the outer section having a plurality of outwardly struck vertical channels "terminating near its lower end, the inner section having outwardly struck stops at its upper end, said stops riding in said channels and serving to arrest upward removal of the outer section from the inner section, short horizontal channels extending in olfset relation from the lower ends of the vertical channels, whereby said outer section may be turned somewhat after being pulled upward, the resulting entry of the stops into the horizontal channels serving to hold the sections in extended relation.

4; A vacuum tube shield for a tube used in an electronic device, said shield comprising two generally cylindrical conductive sections, one section having a diameter slightly greater than the other so that one section is telescopically slidable over the other to a shortened length which exposes the upper portion of the tube for seizure for removal or replacement, and an extended length which shields the tube, and means to secure one section of said shield to said electronic device, the outer section having a plurality of outwardly struck vertical channels terminating near its lower end, the inner section having outwardly struck stops at its upper end, said stopsriding in said channels and serving to arrest upward removal of the outer section from the inner section, short horizontal channels extending in offset relation from the lower ends of the vertical channels, whereby said outer section may be turned somewhat after being pulled upward, the resulting entry of the stops into the horizontal channels serving to hold the sections in extended relation, said horizontal channels being necked slightly at a point between the vertical channels and the ends of the horizontal channels, thereby providing auxiliary detent means to hold the outer section in locked relation to the inner section.

5. A telescopic tube shield construction for shielding an electron discharge tube associated with a support comprising inner and outer tubular sleeve means, one of said sleeve means having fastening meansat its bottom edge thereof for securing same to a support, the other of said sleeve means being axially movable and then circumferentially rotatable with respect to said fixed sleeve means, one of said sleeve means being provided with at Reler'ences'Ci'ted in the file of this patent UNITED STATES PATENTS 825,810 Cooke July 10, 1906 1,447,949 Hall et al Mar. 6, 1923' 1,782,443 Ramsdell Nov. 25, 1930 1,809,355 Powell July 9, 1931 1,827,396 Luckett Oct. 13,- 1931 2,118,665 Churchill May 24, 1933 2,586,946 Haas Feb. 26, 1952 2,911,458 McKee Nov. 3, 1959 2,961,477 Slisz et a1 Nov. 22, 1960 FOREIGN PATENTS 352,733 Great Britain July 16, 1931 Great Britain Jan. 19, 1948 

